The CCA519 Y-splitter for using two Clarion CeNet changers is $75.
Would it be possible to just splice the end of the cable that came with the second changer onto the existing cable, thus effectively making a Y-splitter out of the two cables?
Anyone ever try this, or have an opinion on whether this would work or not?

Only problem I can see is trying to insulate each separate Wire once they are spliced together, and I am assuming that each of the internal wires is color-coded to separate colors.

You can splice them together. If you take apart the y splitter you will see thats all Clarion did. Just go pin for pin and heat shrin all the connections you will be fine. Careful with the audio wires as they are coax lines.

And don't forget to readdress the second changer to another 'number'... IIRC correctly they can be set from 1-4 right next to the cenet plug, but it Is/Was SUGGESTED by Clarion in the changer install manual when they first came out that you only use 3 and/or 4. (im guessing the DSP and tv tuner (the only other devices available at the time) used address 1 and 2)